The present disclosure relates, in general, to electronics, and more particularly, to circuits and method for providing power to electronic devices. In the past, various methods and structures were used to form switching power supply controllers, such as pulse width modulated (PWM) or pulse frequency modulation (PFM) controllers. The switching power supply controllers typically attempted to regulate an output voltage to a desired value.
Fixed frequency controllers, such as fixed-frequency PWM controllers, often did not respond quickly to load transients. For example, some fixed-frequency PWM controllers did not provide a consistent response to a rapid step change in the load. Also, these fixed-frequency PWM controllers often had beat frequencies that resulted in noise in the output voltage.
A Ramp Pulse Modulation (RPM) based controller is a type of PWM controller that can provide improved transient response by determining a duration of phase pulses using an average current of the output voltage. However, RPM controllers using a ripple of the average current to determine the duration of phase pulses do not function properly under certain combinations of input voltage, output voltage, and number of phases. Furthermore, phase alignment in an RPM controller using a ripple of the average current (that, the uniformity of phase distribution over time as the load varies) may be poor and may be sensitive to variations in printed circuit board (PCB) layout. This may result in some phases providing a disproportionate amount of the total output current of the power converter.
Accordingly, it is desirable to have power supply controller that can operate over a wide range of input voltage, output voltage, and phase number combinations, and in particular with a low input voltage, a large number of phases, or both. It is desirable to have power supply controller that can support pulse overlapping among phases in steady-state operation and good phase alignment.
Those skilled in the field of the present disclosure will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the embodiments.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments. This avoids obscuring the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the disclosures herein. The details of well-known elements, structures, or processes that are necessary to practice the embodiments and that are well known to those of skill in the art may not be shown and should be assumed present unless otherwise indicated.